I have an 87 yj it squeaks all the time.
I took of the serpentine belt thinking was a pulley. It wasn't. then I thought that was a pilot bearing so I push the clutch and still made the noise. It squeaks more when i push the throttle. It is a 4.2.

it is probably your altenator or AC unit if you have one lossen the bolts that allow it to slide then take a pry bar and stretch the belt very tight hold it and tighten the bolts so it does not move. I just did this a month ago.

It may help to have someone else tighten the bolts while you hold it tight with the pry bar.

Good luck

Add belt dressing afterwards to help with the squeak.

if after that it still squeaks then your alt or AC could be going bad.

Not sure where it is coming From. I ran it for maybe one min... Could it still be the pilot bearing?

doubtful..without hearing it in person I would say the most likely part doing the squealing would be the throwout bearing..this is the part on the clutch slave cylinder that rides against the pressure plate..if you replace it you could go ahead and replace the pilot bushing while you are in there

someone else might have other thoughts on what it could be..just hang around and wait for a few to see this thread...I know sometimes it is near impossible to do but if you can narrow down where it is coming from that might help